Both USEPA and NHDES define emergency operation of stationary engines based on the type and amount of operation of the device. As these definitions are slightly different, NHDES has prepared the following streamlined definition of an emergency engine that meets both regulations.

An emergency engine is a stationary internal combustion engine used for emergency purposes that is limited to 500 hours of total operation during any consecutive 12-month period. This includes:

Operation during emergency situations. Examples include engines used to produce power when electric power from the normal power source is interrupted or engines used to pump water in the case of fire or flood, etc.; and

Operation for 100 hours per calendar year for any combination of maintenance checks and readiness testing and Emergency Demand Response.

Emergency engines shall not operate as a load-shaving or peaking power production unit.